by Nicole Auerbach, USA TODAY Sports

by Nicole Auerbach, USA TODAY Sports

Training was grueling, events were demanding and focus was single-minded. His life was spent in - and his mind and body bound to - the pool.

And it worked. Michael Phelps has won a record-setting 18 Olympic gold medals and 22 medals overall. But it also led to Phelps calling it quits after the 2012 Olympics in London.

But retirement didn't last long, as Phelps returned to training seriously last year, and he returned to competition this past April, with plenty of time to prepare for the 2016 Games in Rio de Janeiro. He's entered in four events at the U.S. national championships, which begin Wednesday.

"Retirement was pretty boring, to be honest," Phelps, 29, says. "It's funny - I literally would do nothing. If I was at home, I'd always try to, like, golf, or do something with friends, but everyone was working. Everyone had a job. I'd call and text people. I'd either go to the range and hit balls by myself. It got really boring. I'd never be home. I was always on the road traveling and seeing different people.

"It's good to have some structure back in my life. That's how I've always been. That's something I need. I was happy to get that year and a half where I did whatever I wanted, went wherever I wanted. I got that out of the way, and I'm happy to have this back."

Phelps adds that he and longtime coach Bob Bowman have both become more relaxed. "We have gotten older and looked at things differently," he says. "There's a lot more smiling, I think, on the pool deck now than there was in the past."

Allison Schmitt, a six-time Olympic medalist who trains with Phelps in Baltimore, agrees. She says she still sees his fire and passion, but also more smiles when he walks into practice.

Without the jam-packed schedule of Beijing and the pressure to go 8-for-8 in gold, or the push to become the most decorated Olympian in history in London, this time around looks and feels quite different.

"I don't feel like there's any pressure on me," Bowman says, laughing. "He just seems to be enjoying it, and that's what I like the most. He didn't really enjoy it before London. He has a real enthusiasm for it. he's doing it because he wants to, not because he has to. That's the big difference."

Phelps is spending significantly less time training than he did in the lead-up to London as well. He's focusing on shorter events - and no 400-meter individual medley - so training takes up about a third of the time it did previously. "So, that makes it easier, too - a lot more enjoyable," Bowman says.

Here in Irvine, Phelps is entered in the 100-meter freestyle, 100 butterfly, 100 backstroke and 200 individual medley. These national championships, along with the Pan Pacific Championships in Australia later this month, will determine the U.S. team for next year's world championships, which will be held in Kazan, Russia.

"It'll be interesting to see what happens," Phelps says. "We're getting down to that time. This is always a big summer for U.S. swimmers because we pick two teams. You really have to be ready this year. If you're not, you're pretty much sitting around until Olympic trials."

Bowman says he's been careful to avoid having any expectations throughout his pupil's comeback. When asked if Phelps is where he should be, two years out from Rio, Bowman says Phelps is in a decent place, though he could always be faster.

"He knows he has to do more if he's going to move up a level," Bowman says. "He's at a pretty good level, but he knows he's going to have to go back and put in a lot more next year if he wants to really get close to his old self. I don't know if he wants to do that. We'll see."

Wait and see has been the mantra all along. Taking more than a year off from swimming left Phelps out of shape. His' first six weeks back in the pool were the hardest part of the return, Bowman says. Conditioning was and still is a focal point.

"I think he was surprised how hard it was, how fast you lose it," Bowman says.

Eating better and paying more attention to recovery were important, too.

Meets helped provide motivation, and they allowed Bowman a chance to gauge Phelps' swimming. This week will provide the best gauge yet, and the guide to which events to focus on in the future.

"There's a desire to get some of his events closer to where they were - not the amount of events," Bowman says. "The short things he's doing now, that's fine. ... One of the things we'd hope for him is he'd swim all relays, so that's three events. You don't want to be adding too many more. You don't want to add too much. It becomes a lot when you're swimming six, seven events."

A heavy workload also adds to those outside expectations and the pressure that Phelps and Bowman have enjoyed avoiding. So for now, they plan to wait and see how this meet goes, and then re-evaluate and discuss next steps as Rio begins to slowly come into focus.

"Everyone was like, 'Why is he coming back?' " rival swimmer Ryan Lochte says, laughing. "I was like, 'Probably his golf isn't going so well.' I can't see golf being as competitive as getting on the blocks. ‚?¶ Bottom line, I'm glad he's back. It's great for the sport."